Ftoe control system for aircraft



' AIR SPEED Sept. 25, 1945. E. w. CHAFEE 2,385,343

FIRE CONTROL SYSTEM FOR AIRCRAFT GUNS Filed June 3, 1938 3 Sheets-Sheet 1 AZLSPOT EL. SPOT FRICTION BRRLKE INDlCATOR MATCH AIR SPEED INVENT R [flfia AZLREPEET/ A BACK I 1 ATTORNEY g Sept. 25, 1 945. v E. w. CHAFEE 2,385,343 I FIRE CONTROL SYSTEM FOR AIRCRAFT GUNS Filed June 3, 1958 s Sheets-Shet 2 CONSTANTJPffD MOTOR All. com'nol. "r9 sun I fa rl W. ckajeg Hi6 ATTORNEY v OWKV L p 1945- E. w, CHAFEE 2,335,343

' FIRE CONTROL SYSTEM FOR AIRCRAFT GUNS Filed June 3, 1938 3 Sheets-Sheet 3 INVENTOR Patented Sept. 25, 1945 assasrs 7 FIRE CONTROL SYSTEM Fort AIRCRAFT Earl W. Chafee, New YorkQNflYz, assignor to Sperry Gyroscope Company,- Inc N. Y.,- a corporation of New York: U

Application June 3, 1938,;Serial No. 21 1,5501

17 Claims.

This invention relates to a special case of fire control apparatus adapted for directing gunfire from one airplane at another airplane, such as where a high speed attack plane is trailing a bomber, in which case the attacking plane by its superior speed is enabled to maintain a fairly constant range and fly a course parallel to that of the target thereby maintaining a constant sight angle in azimuth and elevation. However, provision is preferably made in the apparatus to take care of continuous rate'of change of angles in both azimuth and elevation. My automatic sight and computer provides a means for sighting and tracking the target, for obtaining the range thereof, and the air speed of the attacking plane, and automatically computing azimuth and elevation deflections therefrom. It further provides means for training the guns from such sight. Preferably the computed deflections are applied in both azimuth and elevation between the line of fire and the line of sight.

In the preferred arrangement, the movement of the control handle at the sight controls the guns instead of the sight, while the calculated deflections are put in between the repeat-back from the guns to the sight, so that the line of sight is thus moved away from its former posi-q tion. This motion of the telescope is not a sudden motion, but fiows in gradually while both telescope and gun are being trained on the target. Therefore the gun is automatically trained and elevated to its correct position for firing by Figs. 1A and 1B are the two halves of a diagram,

showing my improved sight, range finder and computer.

Fig. 2 is a perspective view of the wind resolving mechanism thereof.

Fig. 3 is a diagram showing the principles of operation of the range finder employed therein.

movements of the gun. The motion thereof is transmitted in azimuth and elevation components the former being transmitted by the rockinggpfthe-handle into and'out of the Figs. 4A and 4B are diagrams illustrating the passage of light rays through a part of the optical system of the range finder.

Fig. 5,is-a detail of the mechanism for, rotating the line of sight in elevation.

Fig. 6 is a detail of the range computing mech-L plane of the paper, which'rotates shaft 2 through a gear sector 3 and pinion 3', shaft 2 connecting with --azimuth;control 'l, the output shaft 2' of which operatively connects with, the azimuth drive mechanism of gun (see Fig. 7). ,Rockingoflever; l-in-the plane of the paper moves the rack bar 4 11p and down to rotate pinion 5 and shaftsi and 6,,shaft 6, connecting with elevationcontrpl- 3, theoutput shaft 6' of which operatively: connects; with the elevation drive mechanism-,pf the gun. Theshafts 2 and 6 do not, of,- ;-cou rse, actually move the-gun directly, but througha servomotor system which for illustrationmay ,be similartothe well known Waterbury type of hydraulictransmission, herein representedby the dotted line rectangles Land 8. The output shafts Zf and 6! from the azimuth and elevation controldevices 1 and 8-position the gunin azimuth and elevation, respectively. Referring specifically to Fig. 7, gun I00 is supported by mount ID] for rotationin' elevation about horizontal trunnion I02, this, rotation being effected; in the embodiment illustrated, from shaft 6.' by meanspf worm Hi3: meshing withgear seg- -ment lM carriedby thegun. Mount I0! is rotatedinazimuth about a vertical axis from shaft 2' by means of ,worm H16; meshing with worm wheel I05 fastened to, or integral with the mount. The azimuth and elevation repeat-back shafts 9 and; i0 are -connected with-the gun and may be driven from shafts Z5'and-6', respectively, through gearing as shown. Shafts 9 and I0 have certain corrections applied thereto within the computer and then actuallyturn the line of sight in azimuthand elevation relatively to the gun by actuating-;-movable parts of a telescope 2|22 of a type known as a panoramic sight.

The line of sight enters the eye-piece:l3 and passes-horizontally through penta prism'ld, and

thence"vertically through a pair of reversely rotated wedge-shaped prisms l5 and Is. Said wedges 1 are, oppositely turned by being mounted inannulargears; I Bfrotatedfroma shaft l1, pinion 11;; and reversing gearing l8, shaft I! being turned-fromtheknob [9. After passing through the Wedge-shaped prisms, th line of sight passes through a rotatable erecting prism 20, telescope tube zt;and-angularly tiltable prism 22, whence the line of sight emerges laterally toward the target.

The line of sight is represented as rotatable in azimuth from shaft 23, which turns the assembly on which prism 22 is mounted through pinion 24 and gear 25, while the line of sight is tiltable in elevation by means of a rod 26 pivoted to datum up and down movement of rd 2'6 rocks' the prism 22 about a transverse axis 22' to give the line of sight the proper elevation movement relative to.

the gun for all positions of the: prisminazimuth.

In Fig. 1B, I have schematically represented an. 7

optical sight together with the associated mechanisms for rotating the sight both in elevation and in azimuth and it should be understoodthat the mechanisms for imparting elevation move: ments thereto or movements of the prism 22 about the transverse axis 22" are preferably arranged to rotate inazimuth therewith insubstantial conformity with wellknown practices in this art.

The Wedge prisms l5 and I6 are used infinding the slant range of the target. They are circular glass discs which may have their inward faces parallel and their outward faces inclined thereto at a small angle and which can berotated' in opposite directionsby the above described gears l1,

l8 and knob I 9. two wedges optically act as one single wedge with the wedge angle variable from zero to a maximum, the resultant wedge angle being propor-- tional to the sine of the angle through which the wedges are relatively turned. Fig. 4A shows the wedges with their inclined outer faces parallel.

In this position the bending of a light ray by one wedge is neutralized by a bending in the opposite direction by the otherwedge so that the emerging" B represents and. entering paths are parallel. such a ray, the slight offset which occurs in passing through the double wedge not being. shown.

The position in Fig. 4A is referred to as the neurays entering the wedge area-will go through the hole without deflection as illustrated by ray A', while the balance of the rays pass through the wedges proper, which results in a refraction of the rays. A person looking through the eyepiece will hence seetwo imagesof the target, one direct image (a), Fig. 3, and one deflected image (b) Image (b) will be shifted to one side of the direct image (a) in all casesexcept where the two wedges are exactly oppositely positioned, which position is said: to be their neutral position, and the angular distance through which the image is shifted depends on the rotary position or the an-' gle between the twowedges resulting from a shift from:v said neutral position and with respect toeach other. In the said neutral position, which isreached by turning the wedge adjusting knob i9 until both images merge into one, this angle is zero. By adjusting the wedges. the deflected image of the aircraft can be brought into a position where its wing tip touches that of the direct This arrangement makes theimage, forming the condition shown at (c) in Fig. 3.

In the triangle thus set up, it is obvious that tan B in which B is the angle between the direct and refracted lines of sight, R is the slant range,-and K is the wing, spread. For the condition illustrated in Fig. 3 with the target directly ahead, K is equal to the distance between the centers of the two images. Since K is known from the type of bomber being. attacked, and since B is known from the setting of the wedges, the slant range can thusv be obtained, being K ta.n B

or, for very small angles,

The angle/B. is moreover proportional to the sine, of the angle through which the wedges are relatively turned, or

B=sin A X C where C is a constant and A. is the angle through which the wedges are relatively turned. Hence we may write This condition of course only holds true" where the target is directly ahead. In case it is not directly ahead, the wing spread will be foreshortened; which may betaken into account by intro ducing the angle the line of sight makes with the fore and aft line of the craft (AZ), so that the (.6): log. R.=log K-lfl'og, cosiAl 'og. (snags).

Log K is set inby turning knob. 31' until the logarithmic dial 32 shows the correct value for the wing spread K. Turning said? knob a1so -rotates a cam pin 34' threaded: through a. rack; bar 33 and also spring pressed against a canr'35i. The position of bar 33; is therefore the algebraic sum of the lift of pin 3.4 and the rotation of? knob 3'1.- Log' cos Aais the. lift of said; cam pin 35 governed from the cam. 35' onthe. shaft of gear 24. Therefore the total motion of rack. bar 33' re ate sentsl'og K-l -l'og cos As.

Log (sin A C) is the liftvalue of the cam. 36', which isturned from. the shaft I 'L governing. the position of the two wedge prisms through gears 31. The; cam pin 3!! carries rack teeth. which, through pinion 39, rotate one arm of a differential 4| Thesecond. arm is rotated from rack 33 through'pinion. 41? and shaft At. The third arm. of said differential therefore, through gears 42,- rotates a logarithmic range dial 4'3 in accordance with the aforesaid Equation 6. Therefore the motion of the dial 43 is proportional to'log R and this range may be set into the machine eitherthrough power follow-up mechanism or from a handle 44 which turns the dial 45 to match dial 43.

If desired, an extra dial 46 together with knob 47 maybe provided for operating in conjunction with the dial 32 for compensating for changes in muzzle velocity of the gun. Variations in muzzle velocity are taken care of by introducing a correction in range by turning'the knob 41, thereby shiftingthe reference line 46' for dial 32.

As explained above, the control handle 1 enables the operator to control the gun positions in azimuth and elevation, but I prefer to provide in addition thereto means for setting in, through variable speed drives, continuous azimuth and elevation movements at adjustable rates. This is accomplished by means of two variable speed drives 48 and 49, the driving discs of which are continuously driven from constant speed motor 50.. The elevation variable speed drive 48 is shown as adjusted from the elevation handthan the friction imposed by shaft 6 so that due to the slippage at 60, a forced rotation of handwheel displaces ball carriage 55 without rotating shaft 6.

Similarly, the azimuth handwheel 5 l controls the position of the roller carriage 55 of the variable speed drive 49 and drives the shaft 2 through slip friction connection 69'. The slip friction connections are provided sothat the control of the gun from the main handle I is not interferredwithby the automatic rate drives.

When the rate handwheels are in use, the operator'turns them tothe desired speed and lets go. 'While the operatoris turning the handwheels, the friction at friction couplings 65, and

60 which is greater than that due to ball carriages 55 and 55' holds one shaft of differentials 52 and 52' thereby imparting rotation to shafts 54 and 54 and moving the ball carriages away from their central positions distances proportional to the rates at which the handwheels are turning. When the operator'lets go, owingtot'ne back drive from the driven elements 58 and 58' and to the frictional loads imposed on the differentials 52 and 52 by the friction brakes 62 and 62' '(Fig. 1A)=, connected through gearing 63' and 63' to shafts 5'4 and 54", the handwheels will keep on turning at the imparted rate and any'change of speed imparted to these handwheels by the operator will be automatically kept up since rollers 53 and 58' will be rotated at rates proportional'to the distances carriages 55 and 55 are moved away from their central posi tions and the motion ofsaid rollers will betransmitted through differentials 52 and 52' to the handwheels. Also, if the operator stops either handwheel from turning, it will remain at the standstill position. Therefore, these handwheels may also be usedas Vernier controls to efifect small changes of the position of handle I.

The linear rate of continuous rotation of the handwheels 5| or 5! is represented ,by. 'the radial distance of the ball carriage 55 from the center of its driving disc, and this rate is transmitted to and made use of in the computer through the shafts 54 and 5 4". The azimuth and elevation rates of change of target position (or approximately the corresponding rates of change of gun position) in the present system are considered to be directly proportional to the pre diction angles in these two dimensions since range is constant and time of flight is closely proportional to range. Such rates, as representative of prediction angles, are algebraically added to the gun position values through differentials 64 and 64', as received from the repeatback shafts 9 and ID from the guns, and the summation of each transmitted to shafts 65 and 65'. I E {W31 i For positioning the line of sight, I therefore employ two factors in both azimuth and elevation (1) the position of the gun as received from shafts 9 and I0; (2) the value of the rate deflections from the rate drive shafts 54 and 54'; and in addition, I employ a third factor (3) the wind corrections as obtained from the computer.

For obtaining the wind deflections in an airplane, the direction of the wind, which is taken to be wholly due to the relative motion ,of the plane and air, is, of course, always dead ahead and. in a horizontal plane and the velocity thereof is the indicated air speed. I resolve the wind velocity into two components in the horizontal plane, (1) across the line of fire and 2) along the horizontal component of the line of fire, i. e., a horizontal component in the vertical plane of the line of fire, which are hereinafter referred to as cross wind T and head wind S. The resolution is preferably accomplished by a resolving mechanism as shown diagrammatically at R in Fig. 1A and shown in perspective skeleton form in Fig. 2. Said mechanism comprises a worm wheel disc "Ill turned from a worm 'H which, in turn, is

' turned through the train or gun azimuth angle The air speed, as indicated from the shaft 9. by the pointer 12 of the air speed meter I05, is matched by the handle 13 and is set into the machine through a difierential I4 and shaft 15 which turns shaft 16 by means of shaft 15' to position the rack bar Tl proportionally to the air speed. The plate H on which said bar is mounted is movable in guide H13 secured to the face of the disc 10 and rotating therewith. Plate 1'! has a hole engaged by a pin 18 on slider 19.

The other side of the difierential I4 is connected. to the shaft 9 to remove the effect-of turning of disc 10 in azimuth upon the radical position of the rack bar 11. The slider 19 .is, mounted for transverse movement in a lateral slideway in the vertically movable T -shaped member 80, through which extends an elongated pinion 6 l Rack teeth 82 on the rear of the slider 19 mesh with the said pinion 8! to rotate-the shaft 83 thereof. Up and down movement of the member 86 is transmitted by means of rack teeth 85 formed on the rear thereof to a pinion 84 meshing therewith, the pinion being mounted on and secured to rotate with the shaft 86. Hence it will be apparent that the horizontal wind velocity introduced from shaft 76 is re solved into two components S and T (see Figs. 1A and 2), S being transmitted to the shaft 83 of the pinion BI and T being transmitted to the shaft 86 of the pinion, their components being also functions of the azimuth angle AZ through which worm wheel 10 is turned.

The resolved. wind components are each introduced into a pair of three-dimensional cams, by which deflections in azimuth and elevation due to. wind. are obtained. The head: wind shaft 83 isshown as axially positioning a cam- 81 through the pinion and rack bar 88 for the factor S. Said cam is positioned rotationally from elongated pinion 89 turned from shaft l, driven from the elevation repeat-back shaft [0 in accordance witha function of the angle of elevation, 1. e. quadrant elevation. Cam 8'! is therefore positioned in twodimensionsfrom quadrant elevation and head wind velocity S, respectively. The lift of the pinthereon, representing a functional combination of quadrant elevation and head wind, axially positions the second cam 80 of the pair 81, 90, said cam being positioned in rotation from the rotation of the shaft 44' turned from the slant range knob 44. The lift of the pin 9| thereon is therefore a function of head wind, slant range and quadrant elevation represents the wind correction in elevation. It is fed: into the differential 9-2 the other side of which is driven from the elevation repeat-back shaft [0 plus the rate correction introduced through dilferential 64 operating shaft 65. The second differential 92 is for the purpose of introducing an elevation spot correction from the handle 93.

Similarly, the crosswind T positions rotationally the cam 94 through shaft 85 and bevel gears 86', which cam in turn is positioned axially from the lift of the pin 95 on the second threedimensional cam 96 of the pair 94, 9h. The cam 95 is positioned rotationally from the same pinion 89 which rotates the cam 81' or, in other Words, is positioned rotationally from the quadrant elevation shaft l0. Said cam, in turn, is positioned axially from the same shaft id" that rotates the cam 90 through gearing 97 and rackand pinion 98, and hence is positioned axially from the slant range. The lift of pin 95 is'hence a function of the two variables elevation and range.

1e cam 94 is so laid out that the lift of the pin 84' represents a combination of a function of the variable cross wind T with certain functions of elevation and range. The relationships between elevation and wind correction and between range and wind correction are obtained from ballistic tables computed from actual firing tests. The lift therefore represents the wind correction in azimuth or the azimuth deflection which is first fed through the differential 99-,

where the azimuth spot correction from handle N10 is introduced, and thence into differential I O-l, where the azimuth rate correction is intro--- duced from the shaft 65' and differential 54'. Finally the sight is positioned in azimuth from the center arm of the differential l0! through the shaft 23, while it is positioned in elevation from the shaft 30, driven from the center arm of the differential 92.

Thefinal effect of introducing the above deflections intothe sight is tocause a deviation of the line of sight from the position it would have had with all deflections at zero. It therefore now points to the point to which the projectile would speed in case of firing, and since this point is not coincident with the position of' the target, repositioning of the line" of sight is necessary. This is accomplished by moving the gun, which action in turn moves the sight back onto the target. This changes the. deflections superimposed upon the direct connection between gun and sight. However, as the gunner is not conscious of this fact and cannot judge the movement of the gun but only that of hisreticle, he will move his control handle until the reticle is on the target. As all thedeflections are generated simultaneously with the moving of the gun, there is no time delay or lag in the whole train of deflection generation and the gun can be fired immediately the reticle is on the target.

As many changes could be made in the above construction and many: apparently widely different embodiments of this invention could be made without departing. from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense Thus, many features of my invention are not only applicable to. the above described method of indirect positioning of the line of sight starting. from the lineof fire, but also to the direct method of positioning the line of fire from the line of sight, in which casethe connections from the repeat-back shafts to the sight are omitted.

Having described my invention, what I claimand desire to secure by Letters Patent; is:

1. In apparatus for applying awind'age correction to the aiming angle of an airplane mounted gun during substantially level flight of the plane, means positioned in accordance with the azimuth angle of the gun relative to a normally horizontal axis of the plane, means for obtaining a measure of the airspeed of the plane as representing relative wind velocity effective in deflecting a projectile fired from the gun, means receiving said azimuth angle and wind velocity from said first two means and supplying as a function of said two quantities a measure of thehorizontal component of Wind velocity across the line of fire, means positioned in accordance with gun elevation angle, means providing a measure of target range, and means receiving said wind component, gun elevation and target rangefrom said several means and actuating wind correction meansgfor' altering the azimuth aiming angle of the gun in accordance with a function of said three received quantities.

2. In apparatus for app'lying a windage'correctionto the aiming angle of an airplane mounted gun during substantially level flight of the plane, means positioned in accordance with the azimuth angle of the gun relative to a normally horizontal axis of the plane, means for obtaining a measure of the airspeed of the plane as representingrelative wind velocity effective in deflecting a projectile fired from the gun, means receiving azimuth angle and wind velocity from said first two means and supplying a measure of the horizontal component of wind velocity along the line of fire, means positioned in accordance with gun elevation angle, means providing a measure of target range, and means receiving said horizontal component of wind velocity, gun elevation and target range from said several means. and actuating Wind correction means to effect automatically an.

sight to a target, air speed means, resolving means actuated thereby and by the gun for obtaining a measure of component airspeed in a direction perpendicular to the Vertical plane of the gunaxis, means providing a measure of target range, a mechanism actuated by and inaccordance with the elevation angle of the gun in said plane and said measures of component wind and range, for computing a windage correction to the azimuth aiming angle of the gun, and means automatically correcting the azimuth aiming angle of the gun relative to the line of sight in accordance with said windage correction.-

4. An inter-plane fire control device for an airplane'mounted gun comprising a sight having members determining a line of sight, means controllable at the sight for simultaneously positioning the gun and line of sight in azimuth and in elevation, means furnishing measures of the airspeed of the firing craft and target range, a computing device including means controlled by and in accordance with gun position for setting azimuth and elevation angles, and means for setting airspeed and range in accordance with the respective measures of said two quantities, said device further including means for deriving from said airspeed and azimuth settings components of effective wind across and along the line of fire and for computing from said components respectively, each in combination with said set elevation angle and range, wind correction angles in azimuth and elevation, and means automatically ofisetting the gun and line of sight in said two dimensions in accordance with said angles.

5. In aerial gun fire apparatus for inter-plane fire during substantially level flight of the firing plane, a gun mounted on the firing plane for rotation in azimuth and elevation, a sight including members determining a line of sight independently positionable in said two dimensions for tracking a target, means manually controllable at the sight for simultaneously positioning the gun and line of sight in said two dimensions, a correction computing mechanism comprising wind resolving means receiving airspeed as determined by an airspeed meter and deriving therefrom settings of horizontal wind components acrossand along the line of fire, including means for supplying to said resolving means azimuth angle of the gun relative to a normally horizontal axis of the craft, means for setting range and gun'elevation in said mechanism, said mechanism being adapted to compute from the quantities set therein, deflection angles proportional to the effect of wind in azimuth and elevation, said azimuth deflection angle being computed as a joint function of cross wind, range and gun elevation, and said elevation deflection angle being computed as a joint function of head wind along the line of fire, range and gun elevation, and means forv offsetting the line of sight relative to the axis of the gun in accordance with said computed angles, whereby the gunner in keeping the line of sight on the target simultaneously corrects the aiming of the gun for windage. 6. Aerial fire control apparatus for directing inter-plane gun fire during substantially level flight of the firing plane comprising, in combination on the firing plane, a gun mounted for rotation in azimuth and elevation, a sight having optical members determining a line of sight independently positionable in said two dimensions, means manually controllable at the sight for simultaneously positioning said gun and line of sight in said two dimensions, means for obtaining a measure of airspeed, means positionable in accordance with gun azimuth for deriving from airs'peed'measures of the components thereof along and across the line of fire, a computing mechanism, means forsetting said airspeed components and range in said mechanism, and means controlled by the gun in accordance with the position thereof for setting elevation angle in said mechanism, the said mechanism computing from the set quantities deflection angles in azimuth and elevation proportional to the effect of wind in said two dimensions, means for measuring rates of gunmovement in azimuth and elevation, means for combining said measured rates 'asrepresenting prediction angles withsaid wind defiections respectively and means automatically operated by saidcombining means producingofia sets between the sight and gun in said two dimensions in accordance with said combined corrections, V

'7. In aninter-plane fire control device for. an

airplane mounted gun, a sight having members determining a line of sight, means controllable at the sight for simultaneously positioning. the gun and line of sightin azimuth andin elevation, means furnishing a measure of the airspeed of the gun carrying, firing craft, a computing device including means controlled, by and in accordance with gun position. for setting azimuth and and elevation angles, means for setting airspeed, said device further including means for deriving fromsaid azimuth and-airspeed settings components of effective wind across and along the line of fire and for computing from said components respectively, each, in combination with elevation angle, wind correction angles in azimuth and elevation, and

l means automatically offsetting the gun and line of sight in saidtwo dimensions in accordance with 'said computed angles.

8, In an inter-plane fire control device .for an airplane mounted gun, a sighthaving members determining a line of sight, means controllable at the sight for simultaneously positioning the gun and'line of sight in azimuth and in elevation, means furnishing a. measure of the air-.

speed of the gun carrying, firing craft, a computing device including means controlled by and in accordance with the position of the gun for setting azimuth and elevationzmgles, and means for setting wind in accordance with measured airspeed, said device further includingmeans :for deriving fromv said azimuth and wind settings a component of wind-across the .line of fire and for computinga wind correction angle in azimuth as a function of said cross wind and elevation angle, and means automatically-cit 1 setting the gun and lineof' Y sight in accordance with saidcomputed angle.

9. In an inter-plane fire control device for an airplane mounted gun, a, sight having members determining a line of sight, means controllable at the sight for simultaneously positioning'the gun and line of sight in azimuth and elevation, means furnishing a measureof the airspeed of the gun carrying, firing craft, a computing device having means controlled by and in accord-' ance with gun position for setti g azimuth and elevation angles, and means for setting wind in accordance with measured airspeed, said mechan sm further including means for derivingfrom said azimuth and wind settings a head wind component along thelineof fire and for computing a'wind correction. angle in elevation as afunction of saidheadwind and said setelevation angle, and means automatically offsettingthe gun and line of sight in accordance with said computed angle.

10. In fire control apparatus 1 use wi h .8 gun mounted on an aircraft for movements in azimuth and elevation and with a gun sight, resolving means including means settable according to the air speed ofthe aircraft and means movable in proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said air speed along the longitudinal axis of the gun, .a pair .of three-dimensional cams arranged for series operation having followermeans responsive to the lift of one of said cams-for imparting movement in one dimension to .the second of said cams, means for moving the second of said cams in another dimension according $9 a measure of range, the output of said resolving means being applied to move said one cam in one dimension, and means connected to move said one cam in another dimension in proportion to angular displacements of said gun in elevation, said cams being so constructed and arranged that the lift of said second cam will impart movement to a follower according to the elevation angular deflection of a projectile due to the air speed of the aircraft.

11. In fir'e control apparatus for use with a gun mounted on an aircraft for movements in azimuth and elevation and with a gun sight, resolving means including means settable according to the air speed of the aircraft and means movable in proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said air speed across the longitudinal axis of the gun, a pair of three-dimensional cams arranged for series operation having follower means responsive the lift of one of said cams for imparting movement in one dimension to the second of said cams, the output of said resolving means being applied to move said second cam in another dimension, means for moving said one cam in one dimension according to a, measure of range, and means for moving said one cam in another dimension in proportion to angular displacements of said gun in elevation, said cams being so constructed and arranged that the lift of said second cam will impart movement to a follower representing the azimuth angular deflection of a projectile due to the air speed of the aircraft.

12. In fire control apparatus for use with a gun mounted on an aircraft for movements in azimuth and elevation and with a gun sight, resolving means including means settable according to the air speed of the aircraft and means movable in proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said air speed along the longitudinal axis of the gun, a pair of computing devices each having a pair of input members and a single output member, the output member of one of said devices being connected to actuate one input member of the other device, means for actuating the other input member of said other device according to a measure of range, the output of said resolving means being applied to actuate one input member of said one device, and means for actuating the other input member of said one device in proportion to angular displacements of said gun in elevation, said computing devices being so constructed and arranged that the output member of said other device will be displaced according to the elevation angular deflection of a projectile due to the air speed of the aircraft.

13. In fire control apparatus for use with a gun mounted on an air raft for movements azimuth and elevation and with a gun sight, resolving means including means settable according to the air speed of the aircraft and means movable in proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said airspeed across the longitudinal axis of the gun, a pair ofwcorn puting devices each having a pair of input members and a single output member, the output member of one of said devices being connected to actuate one inputmember of the other device, the outputof said resolving means being applied to actuate the other input member of saidpther device, means for actuating one inputmember of said one device according to a measure of range, and means for actuating the other input member of said one device in proportion to .angular displacements of said gun in elevation, said computing devices being so constructed and arranged that the output member of said one device will be displaced according to the azimuth angular deflection of a projectile due to the air speed of the aircraft. 7

14. In apparatus for computing the deflection of a projectile due to the air velocity of a gun, the combination with resolving means including means settable according to air velocity and means movable in proportion to angular dis-.- placements of said gun in azimuth, said resolving means providing an output proportional to a component of said .air velocity, of a first displaceable member, the displacement thereof being controlled by the output of said resolving means, a second displaceable member, means for displacing said second member in proportion to angular displacements of said gun in elevation, and means responsive to the displace ments of said first and second members for moving an output element in accordance with the computed angular deflection of a projectile due to the air velocity of said gun. V

15. In apparatus for computing the deflection of a projectile fired from a gun mounted for movement in azimuth and elevation on an .aircraft, .said deflection being due to the air speed of said aircraft, the combination with resolving means including means adapted to be actuated according to the air speed of said aircraft and means movable in proportion to angular displacements of said gun in azimuth relative to said aircraft to providean output constituting a measure of a component of said air speed, of a dis.- placealble member, means for displacing said member in proportion to angular displacements of said gun in elevation, computing means actuated by the output .of said resolving means and by said member, and an output element movable by said computing means, said computing means being so constructed andarranged that said output .element is moved an amount constituting a measure of the angular deflection of a projectile due to the air speed of the aircraft and the angular azimuth position of the gun.

16. In apparatus for computing the deflection of a projectile fired from a gun .on an aircraft, said deflection being due to the :air velocity of said aircraft, the .combination with resolving means including means settable according to air velocity of the aircraft and means movable in proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said air velocity across the longitudinal axis of the gun, of a ,displaceable member, means 01 displacing said member in proportion to angular displace- .ments of said gun in elevation, computing means actuated by the output of said resolving means and by said member, and an output element movable by said computing means, said computing means being so constructed and arranged that said output element is moved an amount constituting a measure of the azimuth angular deflection of a projectile due to the air velocity of the aircraft and the angular azimuth position of the gun. r

17. In apparatus for computing the deflection of a projectile fired, from a gun on an aircraft, said deflection being due to the air velocity of said aircraft, the combination with resolving means including means settable according to air velocity of the aircraft and means movable im proportion to angular displacements of said gun in azimuth to provide an output proportional to a component of said air velocity along the longitudinal axis of the gun, of a displaceable member, means for; displacing said member in proportion to angular displacements of said gun in elevation, computing means actuated by the output of said resolving means and by said member, and an output element movable by said' computing means, said computing means being so constructed and arranged that said output element is moved an amount constituting a measure of the elevation angular deflection of a projectile due to the air velocity of the aircraft and the angular azimuth position of the gun.

EARL W. CHAFEE. 

